For the "bus decoding"...
I have an old Rigol myself (DS1052E), which does not have any logic analyser functions, but I do have a few Cypres CY7C68013A (saleaeaeae Clones) and they work quite well with Sigrok / Pulseview. Pulseview also has 100+ protocol decoders built in, and they're all written in Python (typically a few pages) so you also have 100+ examples to modify and derive your own.
I have a bit experience with a PC based scope, and I found it quite horrible. A scope must have knobs and buttons. For a Logic Analyser however, working with a Mouse works quite good, and the higher horizontal resolution of a monitor is a real advantage for a LA (Vertical resolution is not so important, (especially if you only have 8 channels
.
Another advantage is the small box with short "dupont" wires. Good enough for low frequency measurement ( CY7C68013A samples only upto 24MHz) That sampling is not fast, but plenty for UART, I2C, SPI, low-speed USB, CAN, LIN and lots of other stuff you find in microcontroller world.
If you're intested in LA functions on a scope, then two channels would be very limiting (even 4 is very low). Options for adding ( often 16) logic channels is available for a lot of scopes, but it's relatively expensive. It can be near the price of the scope itself, which is I think mostly for "historic reasons" or decided by "marketing", as it's often not much more then some signal buffering and fancy (and nice) cables.